Anchor-free infrared pedestrian detection based on cross-scale feature fusion and hierarchical attention mechanism

Abstract

An anchor-free infrared pedestrian detection algorithm is proposed to address the problems of multiscale, partial occlusion and environmental interference in infrared images, which make it difficult for traditional algorithms to perform accurate detection. First, a cross-scale feature fusion module is devised to improve the detection performance of multiscale and partially occluded objects. This module fuses the global features of different residual layers and multiscale local region features, thereby improving the multiscale feature fusion capability of the model while expanding the feature receptive field of the backbone network. Second, the object texture features of infrared images are weak owing to the imaging mechanism, which affects the accuracy of detection model. Thus, we construct a hierarchical attention mapping module to enhance the significance of pedestrian features in complex environments while suppressing the background information. Moreover, to improve the detection performance further, a novel dual-branch head detector is designed to decouple the input features from the channel dimension, which can be used for classification and location. Finally, by introducing the anchor-free concept into the network prediction mechanism, the prediction box can learn ground truth regression parameters by itself, thereby simplifying the network structure and improving the model generalization ability. The experimental results demonstrate that the proposed algorithm can accurately detect multiscale infrared pedestrian objects in complex environments and exhibits better objective evaluation indices compared to other pedestrian detection algorithms. The average precision and recall reached 98.78% and 98.67%, respectively.